Call-distributing telephone system



F. M. SLOUGH. CALL DISTRIBUTING TELEPHONE SYSTEM.

APPLICATION FILED JULY I, 19]!!- 7 snsms-susEf 1.

INVENTOR C/ l A Patented Nov. 7, H 922,

F. M. SLOUGH.

CALL TTTTTTTTTTTTTTTTTTTTTTTTTTTT Kin-5a NNNNNN OR F. M. SLOUGH. CALL DISTRIBUTING TELEPHONE SYSTEM- APPLICATION FILED JULY 1, I918. 1,434,968, Patented Nov. 7, 1922..

l SHEETS-SHEET 3.

INVENTOR F. M. SLOUGH. CALL DISTRIBUTING TELEPHONE SYSTEM.

APPLICATION FILE-D .IULY I. I9I8. I 1,434,968, Patented Nov. 7, 1922.

1 $HEETS-SHEEI 4.

INVENTOR WMMIW F. M. SLOUGH. CALL DISTRIBUTING TELEPHONE SYSTENL.

APPLICATION FILED JULY I, I918.

Lqgm gg Patented Nov. 7, 1922.

' 7 SHEETS-SHEE] 6.

INVENTOR F. M. SLOUGH" CALL- DISTRIBUTING TELEPHONE-SYSTEM. 4 7 'APPLICATION mm IULY 1.191s,

1,4;3,4,9 3, v Patented Nov. 7, 1922.

a w O {TWIIHW Wim v A 1H- INVENTOR ?atented Nov. 7, 1922. i

ETEDSTATES PATENT critics.

FRANK M. SLOUG-H, OF FOREST LAVZN, NEJV YORK, ASSIGNOB TO THE STROMBERG- CARLSON TELEPHONE MANUFACTURING COMPANY, OF ROCHESTER, NEW YORK,

A CQRPORATIONOF NEW YORK.

CALL-DISTRIBUTING TEIEPHONE SYSTEIE.

Application filed July 1, 1918. Serial No. 242,776.

.70 @713 whom may concern.

Be it known that I, FRANK M. sLOl'TGI-i', a citizen of the United States, residing at Forest Lawn, in the county of Monroe and State of New York, have invented a certain new and useful Improvement in Call-Distributing Telephone Systems, of which the following is a full, concise, and exact description.

This invention. relates to telephone ex change systems, wherein calls from outlying subscribers lines are automatically extended by electromagnetical means at an exchange, to different operators positions at the exchange.

.lVhile my invention is of wide application, it has a particular application in a system" wherein the distribution of incoming calls to the different operators positions in the exchange switchboard, is accomplished in such a way that the calls will come in to operators call receiving circuits, or in struction circuits, one after the other in a given order, the calls being allotted to certain call receiving circuits of the operators positions in rotation.

An object of my invention is to provide in such a system, means whereby if certain operators .whose positions are thus equipped with a given number of these call receiving circuits fall behind in the number of calls answered, that they may be assisted by other operators whom I may term assisting operators located at over flow positions, and calls may be answeredby the assisting operators thus enabling the call receiving circuit over which the call is made to be cleared and made ready for another call.

Another object is to provide means in such a system. whereby whenever there are a predetermined numberof unanswered calls at an operators position existing on one of these call receiving circuits which are distinct and separate from the operators link circuits as will be'hereat'ter described, that a signal will be so located at the said helping position that it will. indicate to the assisting operator residing thereat, that the first one of the unanswered calls of the first named position is to be attended to by the said assisting operator.

Another object of my invention .is to proride a conversational circuit from 9 call- .operators position.

Another object is to release the call re ceiving apparatus for use at the first operators position to receive an order pertaining to another call if the first callhas been answered by either the first operator or the assisting operator, the said release being effected by either operator after attending to the answering of the first call performing -the act of connecting one of the idle link circuits of the operators position to a different line, the said link circuit being manually selected by the operator.

Another object of my invention is to reduce the amount of apparatus required in the setting up of the connection by the use of a small amount of circuits and apparatus common to a large number of call extending link circuits, and also common to a larger number of incoming call or instruction circuits.

Another object of my invention is to provide in. such a system as before outlined, means wherebythe operator may manually select any desired idle link circuit located on her position, whereby time is saved in the locating and conditioning such a link circuit to be used.

Other objects of my invention and the in vention itself will be more clearly understood from the description of the embodi ment illustrated in the drawings which are a part of this specification wherein:

Fig. 1 shows a plurality of telephone lines, two of which are shown herein, as well as a central ofiice apparatus operating in connection therewith, the substation apparatus of one of the lines being shown in Fig. 1, and the substation apparatus of the other line being shown in an extension of Fig. 1, on the sheet of drawing containing Fig. 5. Fig. 1, also shows a system of interconnecting intersecting trunks provided for the purpose of extending a call originating on one of the telephone lines to one of a plurality of interconnecting trunk circuits which are extended, as shown inFig. 3. Fig. 1, also shows a plurality of code wires from impulse apparatus shown in Fig. 2, and means for extending connections from these code wires to code conductors of the interconnecttrunk circuits, the particular code wires thus extended depending upon the mun erical position which the line occupies on the connector switches shown in Fig. 5. their calling line extending a diiierent combination of code wires. I p r Fig. 2. illustrates a system of cc interrupter wheels. whereby current impulses are caused to be made, there being an interrupter for each nu'meraltrom 'l to 10. and there being tour groups of the said interrupters to denote thousands, hundreds, tens and units digits which may be combined to designate the calling line' numbers. Code wires extend from these interrupter wheels to the line relays illustrated in Fig. 1, one code wire from each set of interrupters be ing associated with each telephone line. A master impulse wire is also extended from an interrupter shown inFig. 2 to apparatus of Figs. 4 and 4 as a starter wire to mark the beginning of a train of impulses and the end thereof, that a' given train of impulses which characterize a given calling line may operate switches of aselec tive system illus trated in Fig. 5, to select the calling line the train of impulses being composed of consccutive series of interruptions 'fr'oni the diiieu ent order of code wires. i

Fig. 8, illustrates a system of interconnecting intersecting trunks simil'arto that shown in Fig. 1, one of the sets of trunks being that before referred to as being extended from F ig. 1, and the other set of trunks being so arranged that the trunks of one set may be connected to a trunk of another set under the control of controlling apparatus shown in F ig. 3; the trunk of the second set being exten ed to Fig. 4, where it is shown terminated in acall receiving or operators in struction circuit. l V

Fig. 4, shows the extension of the call receiving circuits from the trunking system of Fig. 3 and shows o1:) e1'ators apparatus, whereby an attendant operator may connect her telephone set to the call receiving or instruction circuits of her position to receive a call and thus ascertainthe number of the called. line desired by the calling line party. Fig. 4 also illustrates a plurality of instruction circuit-link circuit assisting junction circuits whereby a previously attended instruction circuit, and a subsequently manipulated link circuit may be by the act of an operator in manipulating the linkcircuit, joined together for a given interval wherein selective switches perform the function of interconnecting the said link circuit,and the calling line terminals, the said connection being performed independent'otl the said instructioncircuit or thesaid junct-iOll Qlrcuit.

Associated with the said junction circuits are shown extensions of a plurality of link circuit-s. which link circuits are extended to the disclosure of Fig. 45. Fig. l. shows in ad dition to two instruction circuits completely illustrated, three others incompletely illuf trated and a system of circuit conductors. rciays, etc, whereby upon as illustrated in Fig. 4, whenever three instruction circuits having calls residing therein, the first of the said link circuits will be operated to extend a signal to a diil'erent operatofs position called a helping position and the signals of the link circuit residing in the first position will be altered in character to designate the transference of the call. whereby the helping operator will be apprised of her duty to answer the call. and the first or home operator will be apprised of the transference.

4 shows the main portion of the link circuits having extensions in Fig. 4T as betore mentioned. one of the said link circuits being in Fig. l completely illustrated. the other being incompletely illustrated: there being contained in Fig. 4L also operators set apparatus and ringing generator apparatus for the home operators position.

The helping operators position apparatus is shown in F ig. a extensions of the instruction circuits of Fig. l being illustrated therein for the use of the helping operator. interconnecting junctions are also provided to interconnect the instruction circuits for a brief interval after the operator has performed the act incidental to the making of connection with the called line; this is the embodiment illustrated cilinsisting of placing the plug of the chosen link circuit into the multiple jack of the called-tor line. This use of junction circuit. instruction circuit and link circuit to make a connection is like that illustrated for the home position, the apparatus for which is shown and will be described in connection with Fig. 4;.

Fig. 4? also shows the operators set and operators common ringing apparatus.

F 5, shows diagran imatically a system oi selective switches for extending the terminals of link circuits as illustratedv in the foregoing figures to the terminals or a calling line, such as the line having the substation A shown in Fig. 5..

WVhen the apparatus is taken for use by the manual selective. act of an operator. the apparatus is so arranged that current impulses will be transmitted over a private circuit conductor leading from the right of Figs. 45 or. as the case may be, to operate selective switches indicated in Fig. 5 of an automatic selective system which may be any of the common types known to the art and which in the embodiment illustrated in this description is shown as being such a system s is illustrated and described in the patent Fig. 4.

to A. Lundell, No. 1, 94,85l whereby the apparatus ofFig. 4 under the control of the current impidses controls the operation of the apparatus of: Fig. 5 to connect to the link circuit conductors which are extended from Fig. l through the apparatus of Fig. the talkingcondimtors oi: the calling line. The current impulse apparatus of Fig. 4 is operated under the control of the code apparatus 01 Fig. 2. circuitconductors from which are extended by means of the apparatus Referring now to the figures, l i 2 shows code impulse apparatus herein illustrated as composed of series of interrupter wheels making interrupted contact with operated contact springs. These interrupter wheels are preferably mountedon a constantly rotating shaft not shown and are arranged in four groups of teneachwhieh l term units. tens, hundreds and thousands groups erably the interriuitin c segments of the wheels are so arranged. that none oi those of the second or tens set will be operated duringthe operative period of those of the first set. and the same is true of the third and fourth sets; that is, each set will produce its contact interruptions one after the other;

the thousands operating first. the hundreds second and tens third and the units last in order. there being; a time interval between he operation of each successive group.

Code wires extendbetween the contact springs operated by a diiierent interrupter wheel to apparatus associated. with'the subscribers lines shown in Fine. 1 and 5, and the current impulses produced by the interrupter wheels are relayed through apparatus oi the subscribers lines broun'ht into action by the act of a subscriber making a. call. to a conductor of a call receiving; circuit. siich as illustrated in Fig. 4. the combination of code wires -for each of the lines being different from the combination of any other of the lines. This arrangement provides means whereby automatic apparatus brou v ht into action by an operator in connecting one of the operators circuits of F t or 49 to the called line. will set in operation autom atic switches to extend this operatmrs circuit to the calling line. The automatic switches set in motion are directively controlled by impulses from the interrupter wheels of 2. As soon as the automatic switches have connected the calling line to the operators circuit which has been extended to the called line through the agency of plug and jack, the circuits which set in operation the automat'ic switches and which serve merely for the purpose of an instruction circuit for informing the operator of the designation of the wanted line. revert to common use.

In the embodiment illustrated, I show apparatus to select the particular call receivof Figs. 1, 2 and 3 to that of in a El lug circuit to be used or a given incoming call. the selectio apparatus illustrated in rig. 3 providinp for the consecutive selec tion call receiving; circuitsp These call receiving circuits may he distribute: among a plurality of operators and a sutlicient numher are provided. so that when theapparatus has selected all many OiiilQ first selected call. receiving circuits will have been discharged from use by the connective act of again be condition to rein this way oh te the ity of implicated. lH CQTCOIIDQCUH appara is for these call r ceiving circuits to select busy or non'husy call receiving cirr and 1 also by this means provide a very even distribution of the calls throughthe entire switchboard. In order to reduce the number of such call. receiving circuits necessary, lt provide means under the control. or". an operator to limit the time of use of each call receivinir circuih that is. the call recei i circuit is not required be used for the period oi conversation between. connected subscribers.

the said interconnect "in; circuits The selected interconnecting; circuit will thereupon under the control of the identifying means above referred j to. thru the intervening;

call circuit cause selective switches of an automatic selective switchins, system to operetc to connect the calling; line direct through the said switches to the interconnecting circuit. upon dis'rhargred from the connection and the subsequent operation of the interconnecting circuit is very much like that o a cord circuit in the ordinary manual telephone system. the called-tor subscriber being: sign naled and the supervisinir ot the connection being}; taken care of by signal lamps within the View, oi the operator. and the operator having; access to the connection by listening lreys and capable'oi severing." the connection by disabling the connection switch the interconnecting; circuit.

ld henever'apredetermined nu ber ct answered calls reside in instric. on cir is illustrated in Fig. i. and in the embodiment illustrated in Fig; 4: whep as man: three instruction circuitshave calls residtherein, I have provided ant. n atic operating means to extinguish the calling signal I The cell receiving circuit is tiere-if en home operatofis position such as of such an instruction circuit and to operate the call. signal of the instruction circuit located at the helping operators position, the said signal and helping operators apparatus being shown in Fig. 49 Also by the above automatic operation, a transfer signal is operated at the home operators position, the said signal being individual to the first of the three instruction circuits above stated to have calls residing therein, sothat instead of as has been common practice, the last incoming call to the operators position being transferred when more than a predetermined number of calls reside on the operators position, I so arrange the apparatus so that the first incoming call of a predetermined number is transfer thus ing the subscriber who has been awaiting attention the longest a chance of being answered by a new operator upon whose position there may not be many unanswered calls.

I contemplate, though I do not specifically illustrate, means at this helping position consisting of switching keys whereby any one of a number of helping operators WO1"l" ing in a group adjacent to the helping position, may by suitably operating a switching key answer the call, so that the use of such a helping position or switchboard sect-ion may-inureto the benefit of the subscriber, in that, very rapid answering may be obtained on this helping; position, if desired. Such a switching key in its'sim plest form would be a manually operated threeway switch having four blades and alternate con tacts for each blade co-operatingtherewith.

Having thus described my invention in its broadest aspects, I will now describe the specific embodiment there illustrated in the drawings accompanying this specification, and will also describe the operation of the system from which other objects of my invention than those above referred to will be present.

Referring now to Fig. 1, at L and LL, I show central ofiice apparatus individual to two telephone lines extending from substations shown at AA for the line LL, and at A in Fig. 5 for the line L. Circuit conductors a, Z), 0, (Z, extend from the line circuit L to like referenced conductors of F igx 5 in which figure multiple jacks J1 and J2 are provided for the line L, and connector switch contacts 00, (M and b?) are likewise provided for the line and shown in Fig. 5, the conductors c and d being; the line talking conductors that lead from the apparatus of Fig. 1 to the substation apparatus at A on Fi 5.

Resume now that the subscriber on the line L whose substation apparatus is shown at A, desires to make a call, he will do so by removing the telephone receiver 7 from the hook closing the switch hook contacts s,

and closing a circuit the-rent to bridge the line conductors c and d which lead from that. portion of the line circuit shown in Fig. 5 to the line apparatus of the line L shown in Fig. l, and thru normal contacts 1 and 3 of the line cut-off relay (l and the battery feed tandem windings 4 and 5 of the relay 6 to the positive and negative poles of the central. office source of current, from which. source current will flow windings over the said line to supply encurrentfor the transmitter of the 1 i 1 sucsta A, and to operate tne relay 0.

The relay 6 will thereupon attract its armai'iures closing contacts 7, 8 and 9 in circuits to be described, The contacts 8 and 9 being closed, two co-operating circuits will be thereby completed thru the windings 1i) and 111 of the relay 1). which may be called the line impulse relay, which circuit includes the four circuit conductors u, t, 71 and 2th. These symbols relate to the units, tens, hundreds and thousands digits of the number characterizing the subscribers line L with which the thereby referenced circuit conductors are associated. Similar circuit conductors to a, if, h and th for the line L are provided for all of the lines of the system being described, the conductors an, 2ft, 7th and til-HZ designating like conductors for the line LL.

This description will operation of the system wherein the line L is the calling' line, and the line LL s the called line of a circuit connection to be established, and the establishment of which connection is described.

At the lower partof the sheet of Fig. l are shown four groups of circuit conductors, there being; ten circuit conductors in each group. These circuit conductors I term code wires, the first group of code wires being for the purpose of providing the units designs tion of any telephone line, the second groin) being; provided to designate the tens digit of a telephone line, the third group the hundreds digit and the fourth group the thousands digit tiereof. These code wires are shown extended from Fig: l to F 2. and on F 2 are shown the code interruptwheels for each. of the circuit conductors of the four groups. ther circuit interrupting mechanism than that specifically shown in Fig. 2 may be associated to perform the functions required of the specific structure shown in Fig. 2. In the embodt ment illustrated the code impulse wheels are assumed to rotate synchronously as on a common rotating shaft together with a master impulse wheel 10 shown to the left of the four groups of impulse wheels in Fig". 2, The right-hand. row of impulse wheels shown in F ig. 2 are connected in electrical circuit with the ten code wires of the group TH, each conductor of the ten be confined to the thru the said lit in the group being connected to a different impulse wheel; the bottom conductor of the group shown in Fig. 2 leading to an impulse wheel TH-1, and-the top code wire of the thousands group leading to the,

impulse wheel Tlll0, the first named impulse wheel having a single short circuit interrupting insulating piece in the periph= cry of the conducting segment thereof, and. the last named impulse wheel havingten short circuit interrupting insulating pieces in the periphery of its circuit conducting segment; the other intermediate code wires being connected to impulse wheels having second quadrants in each group oi wheels above mentioned, there is a circuit conduct ing space on the periphery of the wheels considerably"broader than .the circuit cond ucting spaces between the insulatin The two other groups of the che tens and units designations are wheels of the thor ands and hum. eds desi gy nations just described, only the circuit con-- ducting portions and the insulating pieces are arranged just 180 degrees away from the like portions or" the before described wheels in this way. tour wheels for like digits in the different groups will produce a like number ct circuit interruptions, oniv the circuit interruptions will not occur simultaneously, being produced in, regular order one after the other as the tour circuit interrupting quadrants come successively under the brushes attached to the code, wires which are all arranged in the embodiment illustrated, to contact on the same side of the wheels. The, circuit conducting segui oi the thousands as has been described, is connected to the negative pole 0'! battery, the luindred group to the positive pole of battery, the tens group to the negative pole of battery, and the units group to the positire pole oi battery.

The impulse relay 12 of Fig. 1, has its windings 10 and ll placed in series with the units and thousands, the tens and hundreds code wires, respectively, by the operation of the relay 6 closing contacts 8 and 9 as before described, and each wheel of the two pairs produces current impulses of differ:

These 0on ent polarity. It is apparent that current impulses will be produced in the circuits described, thru the said windings 10 and 11, producing sets of magnetic impulses one after the other in the coreof the said relay, sothat the contacts 13 thereof will be vibrated to produce successive trains of current impulses characterizing the four digits comprising the number or" the calling telephone line. The short contact piece of the wheel N which is connected to the ground pole of battery as will he later more fully described produces a single impulse of current over 'ts connected conducting wire after the associated circuits as will be later described, are properly conditioned, the timing of this single current impulse being such that it will occur just before the thousands train oi circuit interruptions begin. The circuit conductor leading from this master impulse .vheel leads to the interconnecting circuit mechanism. of Fig. l which will be later described.

When the relay 6 was operated, contacts? were also closed completing a circuit from the negative pole of battery, thru the resistances and 151 to the ground pole of battery, and thereby raising the electrical potential of the circuit conductor 15 leading thru the winding 17 of the line cut-oil relay C of the line and the circuit conduc tor a leading to like referenced circuit conduct-or a of Fig. to the thimbles of the multiple jacks J1 and JQ'of the callingline.

This raises the electrical potential of the said multiple ack thnnbles and conditions the line to test busy when the ordinary manual busy test is made by touching the plug ct anlinterconnecting circuit to the said tliimbles in the usual manner. A. branch circ it is also closed by the contacts 7, the circuit being traced'thru the said contacts and a winding 18 of a connection relay l9, and thru normal contacts 20 wt a relay 21 to the ground pole of battery.

The object of the completion of the circuit just traced, is to interconnect circuit conductors c, d and f of the calling line to an intersecting trunk circuit, such as the trunk circuit B or the trunk circuit D, the trunk B in the description being taken as the seized trunk circuit, but it the trunk circuit B isbusy, that is, taken for use by another line such as the line LL, the relay 21 would have been operated, and the contacts 20 opened so that the circuit'just traced includ ing a winding 18 of the relay 19 would not have been completed, but instead a circuit would have been completed comprising a winding 18 D of a relay 19 D. the circuit being established through contacts 20D of a relay 2]. D, all associated with the trunk. D, and having parts which correspond to parts referred to for the trunk 13. Likewise it the trunks l3 and D were busy, the next succeeding trunk would be seized for use upon the initiation of the call by the subscriber at A as described. The circuit just traced being completed, current will flow over the same fromthe source of current included in the circuit thru the winding 18 of the relay 19, and then will cause this relay to be energized thereby attracting its armatures and closing contacts 22, 23, 24 and 25.

The contacts 22 being closed, a holding circuit is thereby established for the relay 19, including its winding 26, the circuit being traced as follows: from the negative pole of the source of current, the now closed contacts 7 of the relay 6, the winding 26 of the relay 19, the now closed contacts 22 thereof. the winding of the relay 21 which is individual to the trunk circuit and common to the group of lines capable of being connected to the trunk; the circuit being thereafter traced thru conductor R which leads to a like referenced conductor R on Fig. Where the circuit of the trunk line maybe seen extended, and thru the winding of the relay 2? to the ground pole of the source of current. of the relay 21 to open contacts 20, whereby another line may not be connected to the trunk line B, and will cause the contacts 28 to be closed extending the circuit of the con necting ground or the trunk seizing circuit to contacts of a like relay for the trunk circuit D which is assumed to be the next succeeding trunk circuit capable of being seized for use by a calling line. The relay 27 will also be operated in series with the relay 21, and will attract its armatures closing contacts 29 and 30. The contacts 29 being closed, a circuit will be completed including the said contacts traced as follows: from the negative pole'of the source of current thru the said contacts 29 and, winding 31 of the relay 32, contacts 33 of a relay 34, a brush 35, a contacting segment 36 of a rotary switch SW and thence thru the winding of a relay 37 to the ground pole of battery. This circuit being closed, current will flow over the same operating the relay 37, which being of very high resistancewill so limit the strength of current flow, that the serially included winding 31 of the relay 32 which is of relatively low resistance will not energize the relay 32 siidiiciently to operate its contacts. The relay 32 and a like relay 132 for the trunk line D, are arranged to interconnect a call receiving circuit M to the associated trunk line B or D.

In this description, although but two trunk lines of each type are shown, it is understood that other trunk lines might be employed in practice to increase the volume of service as may be required of the trunks.

The relay 34 is individual to the call receiving trunk line circuit M and is common This [will cause the operation to all of the trunk lines B and D which may have access to the trunk M. The switch SW and the associated magnets and 38 together with associated. apparatus is common to all of the call receiving trunk lines, such as M and N shown in the drawing of Fig. 3, and operated to condition a next succeeding call receiving circuit for a subsequent call upon the establishment of a preceding call connection whereby an incoming trunk line, such as B or D is connected to a call circuit.

It is understood that other forms of interconnecting switch mechanism may be employed to produce the interconnection of the trunk lines of the various types, such as ro tary switches or cross-bar switches, as are a part of the art.

The relay 3'? having been operated, the contacts 39 thereof will be closed completing a circuit including the source of current, and the completing of the slow releasing magnet 38 which is the motor magnet for the switch SlV, the switch SW being of the backstroke type, being propelled from one operative position to another upon the deenergization of the slow releasing magnet 38, which may be made slow releasing in any suitable way. The magnet 38 being operated, the armature thereof will be attracted and will cause the carried pawl to fall into the next succeeding notch of the ratchet wheel PCW, so that upon the deenergization of the magnet 38 which now takes place, the ratchet wheel nw will be propelled by the action of the spring 40 to its next position of rest causing the next operative position of the switch Sil The magnet 38 being energized, contacts 41 will be closed upon a fullattraction of the armature short circuiting the high resistance relay 37. This will produce a slow releasing of the armature of the relay 37 and of the slow release relay 38, but in the meantime will accomplish the operation of the relay 32 by increasing the flow of current from its winding 31 in the circuit which has been described.

The relay 32 having been operated, a looking circuit will be completed therefore, including contacts 42 and a winding 43 there of, and windings of the relays 34 and of the call receiving circuit, the relay 44 being shown in Fig. 4. This locking circuit is traced as follows: From the negative pole of the source of current thru the contacts 30 of the relay 3?, the contacts 4 and the winding 43 of the relay 32, the winding of the relay 34, circuit (I'Ollfll'ltftOl' 'R which is shown in Fig. 4, and the winding of the relay 44 to the ground pole of the source of current. Current from the said source will flow over the said circuit. causing the relay 32 to remain operated and causing the oper ation of the controlling relay 34 and the re lay 44 of the call receiving circuit. The reswering signal lamp 46?, thru normal conj tacts 4:8 of a relay 49 this circuit includin the source of current, and the la r) a? will be operated to apprise the ope r that call exists on the call receiving} i'cuit ill, with. which the lamp l? is associated.

Another call receiving circuit is shown at X in Fig. 4i for the same operators position. Uther call receiving circuits such as N shoim in Fig. 5 lead to call answering apparatus on other operators positions The call circuits M and others not fully shown in Fig. 8, but which it is uncerstooo may be in cluded in the system ol' my invention lead to other operators positions, the iirelferred order in which these call eceiring circuits are allotted for the use or? succeeding iumming calls by the call allotting switch S being such that the first call receiving; circuit oil the first operator will first receive a call, then the first call receivi circuit of the second operator, and then so on until all of the operators have had a call associated by the call allotting switch fil in the first call circuit of each operators posititui. Thereutter the said call allotting switch will allot calls to the second call receiving circuit in order to each positniai until calls have been allotted to all call receiving circuits which. preferably may be live in number for certain conditions in telephone traffic which are obtainable in practice, whereupon the call alletting switch SW will again allot a call to the first call circuit or the first operator and 'so on it being proposed to thus distribute the calls. in absolute rotation as to-call circuits and as to home operators positions. The line talking conductors c and (Z orthe calling line have now been ex ended by means of contacts 23 and 24L of the relay iii) of Fig. l, and by contacts 50 and 51 ot' the relay 32 of F 3 to the listenin hey springs 52 and oil the listening key o4 of Fig. a.

The so-called home operator may now answe'i' the call on the call receiving circuit by operating the listenungkey and closing the contacts thereof to connect her operators telephone set shown at Q in F a, to the talking conductors of the telephone lnic extended as described The operator coinvcrsing with the subscriber will learn the number of the called-for line. In the operation of the listening key, contacts were closed completing circuit for the relay 419. the said circuit including the source of curcuit the resistance coil 14, and the winding 1 from the negative source or. current to the rent, the winding or the 52 I and contacts of no opera ed rr. i l. This will cause the relay 49 to be operated which immediately s the iockinncircuit for itself including its winding and its contacts 56, independent oi the i oil. the listening key. The list may now be opened, the relay l9 l'Gillh operated through its locking contacts. a signal lamp is stinguished and a {amp 5? will belighted in its place to indicate that the call on the call receiving" cirhi. has been answered, but the de 1redfor connection not yet completed.

The circuit for the lamp 5? includes now closed contacts oi the relay a9 and normal contacts 59 oi the relay 60, and coin tacts 4-6 of the relay together with ci ,cuit conductors leading through the said I contacts, and including the source of cur not. '85 Tie operator having learned the number of the called-tor lin'e,will now complete the connection by means of one of a pluralityoi ronneztion switches vrider her control and which are herein ill istrated as being plug and jack manually operated switches. The operator may use any connecting plug oi. the group provided for the purpose, and time is thereby saved in completing connection, since an operator upon completing one connection by manipulating one connection plug, may immediately manually pro-select the plug "for the next connection by pickingv up such a plug as she desires to use for the llGlCi? connection.

lnthe illustrated form of my invention l arrange multiple jacks of the called lines on the operators position in proximity to the said phig whereby the operator may by inserting the plug into the said multiplejac-lrs, make connection with called lilies. Such an actwill cause an association of the call re ceiving circuit last attended and the particular plug circuit manually selected. This is nota permanent association as will be seen from the further description.

To continue the narrative, the operator having manually selected an idle plug circult, will make the busy test in, the usual. way by touching the tip of the connecting plug, such the connecting'plug Pl, shown in F 4%, to the thin'ible oi the called line jack which we will assume is the jack J3 for the called line Lli. shown in Fig. 1.. It the called line busy the busy condition of the line will be indicated to the operator by the existence of a raised potential of the jack thimble ot' the jack J3 with. reference to the potential of the ground pole of the exchange source of current. This is accomplished by the means shown and described for theline L consistingrv of the contacts 7 of the relay 6, y

K of the relay C- which provided a circuit llO" shank or" the plug to which is connected a circuit leading to the negative pole of battery makes contact with the said thimble to the potential thereof. It the line is busy, current from the said negative pole of the source of current will when the busy test is made, traverse the tip of the talking strand 461 of the connecting circuit OP thru normal contacts L62 of the relay i655, and normal contacts 464 of the relay 465 to the common test relay l66 for th operators position, and thru the said r ay to the ground pole of the source of current, energizing the said relay, causing it to close its contacts 4-67 and thereby establishing a circuit for the flow of current from the source of current including an inductive winding 168 on the operators induction coil inductively related to the operators receiver $69, which will thereby be operated giving the characteristic busy click. The operator will thereupon tell the subscriber that the line desired is busy. The subscriber by restoring his receiver to the hook will open the contacts of the hookswitch, releasing line relay 6 which by its contacts 6 operated the relays which have been described as having been operated on the establishing of this connection to the present point of description, and these relays will therefore be released, restoring the apparatus to normal. The operator if she does not find the line busy, will insert the plug P1. for the connecting circuit GP into the ack J3 of the called line, making connection thereby with a pair of talking conductors of the line and a local private wire of the line circuit to like talking conductors and a. private wire of the connecting circuit OP. A circuit will thereupon be closed including a winding of the cutofi relay 71 of the called line and the winding of the relay ot the connecting circuit, the said circuit including the source of current; current from the said source will flow over the said circuit energizing these relays which will attract their armatures.

The contacts 72 and 73 ot the relay 71 of the linecircuit will be opened to remove the normal association between the call initiating apparatus of the line circuit and the line circuit proper. The contacts 74.- ot the relay 71 will be closed placing the winding 75 ot the relay 71 in multiple with the winding 70. The relay 465 of the connecting circuit CP shown in Fig. 48 being operated, will close its contacts 476, 4-77, 478 and 179 and open its contacts 464. The opening of the contacts 464 will dissociate the busy test relay 466 from the connecting circuit. The

closing of the contacts 47 6 will complete the plished connection of the winding 480 of the tip sup e y relay to the talking strand 4:61 of the connecting circuit. The closing of the contact 4-77 will complete a circuit including the source of current and normal contacts 482 of the relay 283 for the supervisory lamp 484, lighting the said supervisory lamp, this association being accomby circuits temporarily established over intermediate switching circuits of which there would be provided only a few for each operators position. The function of these intermediate junction circuits is to extend the circuit of the impulse conductor, such as the conductor 106 of the incoming circuit M shown in Fig. :1, through the apparatus of the connecting circuit, such as GP, to convey the controlling in'ipulse through the said connecting circuit and toswitching apparatus which may be associated therewith. The saidswitching apparatus will then establish a talking circuit from the said connecting circuit, which at this time has established a talking connection with the called-tor line terminals to the talking terminals, of the calling line. in the systemof my invention 1 find that since the time of use of what might be called the impulse sending apparatus; is relatively short compared with the total time ot connection to limit the number of such. impulse conductor extending links or junctions, to a very small number such as 2 junctions common to a much larger number of connecting circuits as GP, and common to a larger number of incoming call circuits, such. as M and X. Such interconnecting links and associated apparatus is shown at T and U, having in the embodiment illustrated, terminal connecting relays 8S and 988 for the junction circuits T and U respectively, wherewith to connect either of these junction. circuits T or ll to the incoming call circuits M, and these junction. circuits T and U likewise have like relays wherewith to connect them to other incoming call circuits such as the line relays shown for connecting to the incoming call circuit. The junction circuits T and U likewise have terminal connecting relays 511 and 512 to connect the junction T or U respectively, to the connectingcircuit CPQ in Fig. 4 and the junctions have also terminal connecting relays 513 and 514 to connect the junction T or U respectively, to the connecting circuit GP of Fig. 4. Common controlling relays and 51.6 for the junction circuit T, and 517 and 518 for the junction circuit U, are provided to perform functions during the interconnection process. which will be apparent from the description of the operation of these relays which follows.

The relay 465 of the connecting circuit CT of Fig. 4 having been operated as described by the act of the operatormaking connection with the called line terminals, its contacts 4'79 will be closed completing a circuit from the negative pole of battery, through the said contacts, through the normal contacts 4:85 01 the connecting circuit 488, over the conductor 519 which is extended in Fig. 1, and through the winding 52:) of the relay 514, through the winding 521 of the relay 517, and through normal contacts 522 of the controlling relay 518to the ground pole of battery. Current from the negative pole t the source oi? current would not flow over the circuitjust traced from Fig. 4 through the winding 523 of the relay 513, for the reason that the ground pole of battery would not be connected to the contacts 524 of the relay 516 as they are to the contacts 522 of the relay 518, since in order to accomplish this, the relay 518 would have to be operated closingthe contacts 525 of the relay 518 to extend the ground pole of battery to the contacts 524 before mentioned. Therefore, at this time the conditions are such due to the relay 518 being inoperative, that the junctioncircuit U rather than the unction circuit T is selected for the linking of incoming call and operators connecting circuits involved in the setting up of the present described con neetion.

The circuit above described being completed, current will flow over the said circuit operating the relay 51 i and the relay 517, due to current traversing the windings 520 and 521 respectively, of these two relays, These relays being operated they will attract their armatures, the relay 521 thereby closing its contacts 526 to cause a further extension of? the interlinking operation. In furtherance of this extension a circuit will be completed from the ground pole of battery,.through the contacts 526, windings 533 of the relay 517, and over the circuit conductor 527 leading to windings, such as 528 of the relay 529 for the incoming call circuit X, to the winding 530, of the relay 988 for the incoming call circuit M.

A circuit is only completed, however, through one ofthe said windings, namely,

the winding 530 of the relay 988, since only the incoming call of operation produced bythe previous answering of an incoming call residing therein, and in consequence to such answering the relay 49 01 this incoming call circuit M has been operated and ,operatively locked to close contacts 531 thereof in the circuit of the winding 530 of the relay 988 to complete the circuit including this Winding which is being traced, this circuit also including normal contacts 532 of relay 60 of the incoming call circuit M. This circuit being completed, the relay 988 will be operated, and the relay 517 will for: the h ocircuit M is in that state ment beretained in operation by current flowing over this circuit. The relays 988 and 51% being operated, a circuit will be completed through contacts 534 and 535 of these relays respectively, the said circuit leading from the ground pole of the source of current, through the normal contacts 536 of the relay 537, the contacts 46 of the relay 141, the winding of the relay 60, the contacts 534, the winding 537 of the relay 988, the winding of the relay 518 of the junction circuit U, the winding 538 and the contacts of the relay 514, circuit conductor 539 which is extended on Fig. 4 and in Fig. 48* leads through the winding of the relay 4186 to the negative pole of the source of current. Current from the said source will flow over the said relay windings serially included, retaining those relays inoperation which have been described as previously operated, and 7 4:86 of the connecting circuit OP, the coil trolling relay 517 for the junction circuit U, and the relay 60-of the incoming call circuit M. The relay 518 being operated will open its contacts 522, thus disabling the relay 512 that another connecting circuit may not be connected to the same junction circuit U. The contacts 525 being closed, extend the circuit from the ground pole of battery to the contacts 524 of the relay 516, through which the ground is extended to the windings of the relays 511 and 513 to condition these relays for opera tion so that it, While the junction circuit U is in use that upon the next succeeding connection being established, the junction circuit T may be taken for use in the establishment of the said next succeeding connection.

The relay 518 being operated, its contacts 541 will be closed short circuiting the winding 533 of the relay 517, and the Winding 521 of the relay 517 having its circuit opened at the contacts 522 of the relay 518, the relay 517 will be disabled and will. return its arniatures to its normal unoperated posi tion, the return being accomplished however slowly, due to the retarding effect of the short circuited winding 533, this so that the holding circuit in which is included windings of relays 988, 514-. and 186 may be completely established prior to any possible disabling of the establishing energizing circuits for these relays. Such establishing circuits are now broken at the contacts 582 of the relay 60, at the contacts 522 of the relay 518, and at the contacts 485 of the relay 186; the latter being in the connecting circuit OP.

The contacts 59 of the relay 60 are now broken extinguishing the signal. lamp 57 to indicate the association, which association is perhaps more directly produced by the lighting of the signal lamp 96, which is hi operating the relays I cluded in a circuit with the source oi? (tin-rent and now closed contacts of the relay 60. This lamp 96 will remain lighted during the full period in which the talking -conductors of the connecting circuit are extended. by the Operation of automatic selective ap-- paratus to make connection with thetalking "conductors of the calling line, as will be described.

The contacts e98 of the relay 486 are now closed completing a circuit from the common master impulse wheel shown in Fig. 2 and indicated as to, the circuit being only completed at such intervals as occur when the short segment 99 makes contact with. the brush 100 to mark the intervals between succesive trains of code impulses denoting calling line number designations. As soon as the contacts 99l00 of the rotating impulse wheel make contact, a circuit is 00111- pleted from the ground pole of battery, through the said segment and brush ot the impulse wheel, circuit conductor 'ww leading from Fig. 2 and extended in Fig. 4 the said circuit being completed through contacts 498 of the relay 4-86, normal con tacts 501 of the relay 502, the winding of the relay 508 to the negativepole oi: the source of current through contacts 478 of the relay 465. Current flowing over this circuit will operate the relay 503. This relay being operated, will close its contacts 504.

When the line conductors c and d of the calling line were extended by means of contacts 23 and 24 of relay 19 of Fig. 1, and by contacts 50 and 51 of the relay 32 of 53 to the listening key springs 52 and 53 ot? the listeningkey st of l. as has been previously described, a circuit was also com-- pleted to extend in like manner the circuit conductor 7 which I call the impulse wire, from the intermittently operated contacts 13 of the relay 12 of the calling line circuit through contacts of the relay 1.9, through contacts 105 of the relay to the conductor .06 of Fig. ii. and which conductor 106 is later further extended by the closing or" con tacts 93 of the relay 988 and by the closing of the contacts of the relay 517 upon the sertion of the plug Pl into the jack of the calling line; the extension being male thereby to the conductor 107 leading through normally closed contacts 508 cit-the relay 509 shown in Fig; land now through the contacts ot the relay 503, the said con tacts having been closed as described by the operation of the relay 503, and over circuit conductor 110 of Fig. 5, and through the winding of the stepping relay 205, to the negative pole of the source of current shown in Fig. 5.

Fig. 5 shows automatic electrically operated switches, together with circuit con ductors and controlling apparatus for the said switches, whereby line talking conductors, such as the talking conductors 111A and 112A of the connecting circuit C1, are extended through contacts of. the said switches to the terminals (:0 and (M of a telephone line having line conductors 0 and d, and as shown in the drawing of Fig. 5 hav ing a substation A connected to the said line conductors.

The switches and circuits employed on the present invention may be of any desired structure to perform the functions desired as above explained, but for the purpose of illustrating my invention, l have illustrated with slight modifications the structure disclosed in the patent to Alben E. Lundell, No. 1,194,851.

In the drawing of Fig. 5 showing this system, 111A and 112A represent the extended talking conductors of the connected circuit UP shown in l? ig. 4i; 203 and 2% represent normally opened contacts in the automatically selected connecting circuit which are closed immediately following the association of the said connecting circuit with the plug connecting circuit of Fig. 4 205 is an impulse relay which responds to nnpulses repeated over conductor 110 to successively operate the stepping magnets of the several switches. Batteries .of different potential are indicated in the drawing of Fig. Certain of these batteries which are indicated as being merely of two cells. may be of Zl volts potential, the other batteries indicated as being oi: .4 cells, may be of 48 volts potential. A selective system produc ing equivalent results to that shown in Fig. 5 and havinga source of current of but one potential may be employed instead of that illustrated.

The series oi? interruptions produced by the contacts 13 of the relay 12 shown in Fig. 1. will now cause the stepping relay 9.05 to retract its armature, opening the circuitfor relay 215 which in turn retracts its armature. Relay 216 being slow to release. rcmains up throughout the series impulses. With each deenergization 01" the relay a circuit is completed from the 48 volt battery. through the primary stepping magnet 217 and the escape relay 218 in parallel. and thence through the front contact and armature of relay 216 and the back contact and armature of relay 215 to ground. h lagnet 217 and relay 218 will both be energized. and relay-218 will. close a circuit from battery through the left winding of the escape magnet. 2M, armature and contact of relay 218', wiper 219 and the right winding; of magnet 21 i back to battery, thus energizing the escape magnet. The side switch. however, will not be operated this time until. the escape magnet is deenergized. Relay 218 being slow to release, is held up during the series of impulses. Magnet 21? rapidly attracts and retracts its armature moving the wiper and stepping relay 215.

time, however, the 24 volt battery at the inibrushes 209, S210 and 211 of the selector switch from group to group of the trunk terminals.

Upon the tern'iineition of the series of impulses. relay 205 will remain energized, and

' will hold the circuit for relay 215 closed. ilelay 218 will then retract its armature, openingthe circuit for the escape magnet 214; and cai'ising the side switch to move to position As the side switch moves to position 3 the circuit for relay 215 is interrupted, and it retracts its armature, buta substitute circuit is completed for the holding; relay 216 through the side'switch wiper l -lin position 3, thus preventing the release of the switch.

The escape magnet 214i is employed as :1. test relay. In position of theside switch, a circuit is closed from the 24% volt battery through resistance 220, wiper 219 and the right winding of relay 214C to ground. The current flowing over this circuit is, however, insutlicient to cause ma it its armature. At this time, a circuit closed from battery through the left windi. 1 oi. magnet 214i and WiperQQ'i to the test b ush 209 of the selector switch. The test or guardinp contacts of trunks leading to idle selector switches will be connected. to ground through a side switch wiper 13 at the-second sclcctor and the left winding of the escape. magnet 214% of that switch.

liiyhowever, a trunk leading to such switch is busy, its test or gua-rding contact will. be provided with battery potential. This may be supplied in several different manners, depending on the stage of operation of the switchwhich has selected the connecting; circuit, and oi the switch at which the circuit terminates the connecting circuit justbeen sele d at one of its multiples and the side switch 01 this connecting circuit has moved to position 2, it is obvious that the test contacts will be connected to the 48 volt battery through At this pulse relay 205 willalso be connected to said test contact by a circuit extending throi wipers 213 and 221, in position i. There'li'i I the po'tentialof the test contact will be of substantially 2 .1. volts, and current will therefore not flow through the left winding of magnet 214 in such a manner as to cause its energizetion. It the impulse wheel connected to theconnecting circuit is at this timetransmitting impulses, the battery at the impulse relay 205 will be removed from the multiple test contacts of the connecting circuit with each deenergization of relay 205, leaving only the 48 volt battery at relay 215 associated with said contacts. The low of current, however, from this battery through the left winding of magnet 214i, is in a. direction to oppose. the flow of current through its right Wind ng, and magnet 21.4

and its test relay or ma lot 214: will n nothc one. need.

ll hen the second, selector switch 7521s moved to position 3, acircuit was established from battery through the ondary stepping magnet 222, wiper 222i and interrupter to ground. This circuit will beinointained and the brushes 209, 21-0 and 211 will be stooped from trunk to tru til the contacts of an idle trunk are e: gag ed, when current will flow through the left winding of me 1st 214; in :1- dii ction to assist the current flowing through its right winding", thus energizing the escape uuignet and moving the side switch to position 4-.

It is obvious from. the preceding description .in what manner succeeding selector;

switches would be operated. The secondary ranged to be substituted by side switch wiper :t'or the primary magnet in the circuit controlled byrelay It is believed this is obvious'and willnot require "further description. I

By means of the apparatus -oi l 1 shown and described or otherwise indicated, the talkingconductors 111A and112E001 the coin i vctin'grcircuit oi Fig 4- are extended to the csllin 'gline having a substation A, this circuit lieing'independent oi". the circuit pro-- 'viously had which may heEcallcd' an instruc tion circuit for the operator om theseid line. A conversationalcircuitis now cornplete .ncluding; the said conductors and coii- 'tacts of the switches of the sys u or Fig. 5

from the calling subscribers line to the called.

subscribefis' line, through the talking conductors 111A and 112A of the connecting circuit of Flg. 4 and contactsGQ andil 0fthe relay 63 '01" the said connecting circuit, and through co-operatinp; contacts of the plug andjack switch Pl J3, by income of which ashas been described, connection is made with the called line LL shown in Fig. l. The ringing o'fthe called substation may nowpr'oceed in the usual manner for manually operatedsystenis.

-The' circuit of the impulse conductor llOA- -llO, of Figs. L and 5, is'controlled i by contactsj508 of the relay 509, and these contacts remaining closed during successive sets of'irnpulses until a series or selector switches of Fig.v 5 are operated as described, to make connectlon with the calling net of the connector switch might be ar-' is second switch to arrive on the multiple "i: contact wlll find batterv potential their line. The conversational circuit established through the conductors and contacts of the switches of the system of Fig. of the calling subscribers line to the plug connecting circuit GP of Fig. 4 is now operative to cause the operation of the bridged subscribers battery feed relay 631, which is now included in circuit with the subscribers line through the said contacts, the circuit includ ing the subscribers instrument and the central ofhce source of current. The relay 631 will thereupon attract its armatures upon the flow of current through the said circuit and from the said source contacts 632 and 633 being closed. The contacts 623 being closed, a circuit will be completed including the said contacts, a winding 635 of the relay 509 and now closed contacts 478 of the relay 465, together with the source of current. Current from the said source will flow over the said circuit operating the relay 509, which will attract its armatures closing the contacts 636 and 637, and'opening the contacts 508, the mechanical arrangement being such that the contacts 637 are closed before the contacts 508 are opened. This in order to maintain the circuit of conductor 110 controlling the selective switch system of Fig. 5 closed, even though the original circuit for the" said switches through the contacts 508 are opened, the circuit being maintained closed through the contacts 637 and the winding of a relay 638, to the ground pole of battery. The relay 638 being included in this circuit, current will flow through its winding and out over the conductor 110, and the relay 638 will be operated, and the relay 205 of Fig. 5 will be maintained operated to hold the established connection. The relay 638 being operated will close contact 639 in the circuit of the calling subscribers signal 640 which will. not at this time be operated, because of the open contacts 634 of the relay 631, the said contacts being in its circuit. The relay 509 being operated, as described, a holding circuit is established therefor including contacts 636 closed by its operation and now closed contacts 478 of the relay 465, the said holding circuit including a winding 641 of the relay 509. i

The selective system of'Fig. 5 having established connection with the contacts of the calling line, a circuit is completed for a winding of the cut-off relay of the calling line, including contacts of the connector switch, circuit conductor 7) of the line circuit leading through a winding 242 of the cut-off relay C of the line circuit, the said circuit including the central oflice source of current, contacts of the selector switch system of Fig.5. and the central ofiice source of current. The cut-off relay G will thereupon be operated, opening its contacts 1 and 3 in the'circuit of the line relay 6 to deenergize the said line relay, and the contacts 2 will be closed to connect the circuit conductors a and 7) of the line together, so that the increasedpotential of the conductor 7) may be duplicated on the conductor a in order to make the test contacts m and 3 of the multiple jack of the said calling line test busy to prevent the intrusion of an other operators connecting circuit. The line reiay 6 ot the line being deenergized, it will open its contacts 7, 8 and 9 to restore the relay 12 of the line circuit, and the relays 19 and 21 of Fig. 1, and 27, 32 and 34 of Fig. 3, together with the relays 44, 49, 60, 988 and 514 of 4; these relays being involved in the connecting system for the instruction circuit which has been described, and in turn successively controlling various portions of the instruction circuit, each of the relays being controlled by preceding relays in the instruction circuit, and the contacts or". the controlling line relay 6 being opened, these relays will be all restored to normal as will be apparent from the foregoing description, allowing the instruction circuit connecting links involved in the established instruction circuit connection to revert to the use of a subsequent incoming call.

The ringing of the called substation is initiated by the depressal of one of the keys K,, K IQ or K depending upon which. station of a party line, if the called line is a party line. it is desiredto signal, and the contacts 640 which are mechanically as sociated with all of the ringing keys will be momentarily closed during the depressal of any of the ringing keys. these ringing keys being mechanically locked in ringing position The ringing relay 463 is operated and the ringing proceeds. The circuit for the ringing relay 463 includes its winding and the contacts 640, together with normal contacts 641v of the relay 483, and now closed contacts 633 of the relay 631, resistance coil 642 and now closed contacts 479 of the relay 465, together with the central oitlice source of current. Upon the operation of the relay 463, the contacts 643 thereof are closed, bridging the contacts 640 of the ring ing' key to cause the locking circuit for the relay 463 independent of the said key contacts.

The contacts 644 and 462 of the relay 463 are now opened, opening the talking conductors leading to the plug P1, which is understood to be now inserted into the jack J3,and the contacts 645 and 646, leading from the key selected ringing generator, such as the generator G1, and the serially included central source of current as 13,. Current from the said ringing generator will flow through the said ringing contacts 645 and 646, through the talking conductors 461 and 647, leading to the called plug, and

menace from. thence throu h the contacts of the plug and jack switch 91 and J3, and over the iine conductors 248 and 249 of the called line, and nrough the windings of the called subscribers telephone bell 250, ringing the said telephone bell. The called subscriber answering his telephone will remove his receiver from the hook, closingcontacts l brid ing his telephone transmitter across the telephone line, and current from the central source of current E flowing over the circuit for direct current thus established, will operate the tri relay 652 in the plug connecting circuit C. of Fig. 4 causing it to close its contacts 653 to bridge the said contacts across the winding of the ringing relay 4-63 to deenergize the said relay and cause it to restore its armatures to normal, o; *ning the ringing contacts 6&5 and .646 and the locking contacts 643, and closing the talking contacts 262 and 644. These lastnamed contact-s being closed, a circuit is COll'lPlGtG from the subscribers substation apparatus through the said contacts, and through windings 480 and 680 of the bridged sulascfibefls battery teed relay @83, and the.

central. o'fiice source of current. Current from the said source operating the said relay will cause the contacts 641 in the circuit of the ringing relay 463 to be opened to prevent the reenergization of the said relay, and the contacts 482 to extinguish the signal lamp '28%. The subscribers are now in con- \ersational circuit and will so continue until the end of the conversational period, whereupon they will restore their receivers to their hooks, opening their respective line circuits. The opening of the called subscribers line circuit and ot the calling subscribers line circuit will be evidenced in the operated plu g connecting circuit GP, by the lighting of the respective signal lamps for calling and called subscribers 6&0 and 48 this being caused by the deenergization of the respective bridged battery feed relay for calling and called subscribers 631 and 488. The operator upon observing the lighting signals will disconnect by removing the plug Pl from the called line jack J3, restoring the cut-oil relay 71 of the called line to its norreal condition and restoring the relay 465 in the plug connecting circuit to its normal deenergized condition. The relay 465 being restored, circuit cont-rolling contacts 4e76, 477, 4:78 and 4L7?) thereof, will be opened to release the apparatus of plug connecting cirm. .1 UP, the contacts 478 being operative to release the relay 503 which thereupon opens its contacts 50% in the circuit of the conductor 110 leading to the relay 205 shown in Fig. 5, the said relay 205 being thereupon restored to normal. The contacts of the relay 205 being opened, the apparatus of the selective switch system of Fig. 5 which is being held operative by the continued closcircuits of the position.

are of these contacts, will be restored to normal upon the opening thereof, and the switc involved in the established connection has been described, will berestored to normal position.

Now assuming that the system as before described in operation, it is apparent dur-. ng busy times oi the day more than one call will be awaiting attention on a given 0perators position and it may be that such an operator, as for instance that operator whose telephone set is shown at O in Fig. i and upon whose position, for instance five inof 2, 3 or more up to 5 unanswered calls, and

it is apparent that in the case of a relatively slow operator, that ii means are not provided to assist in the speeding up of the answering operation, that confusion will resuit, or all of the operators will necessarily be required to answer calls at a rate of speed set by the'slowest operator.

In the system of my invention and by the means now about to be described in detail,

I provide assistance for the slower operators, or for such positions in which for some reason or another, more than a predetermined number such as more than two unanswered calls, have become resident in incoming call A representative operation of the apparatus involved will now be described wherein there are two un answered incoming calls resident in the call circuits M and X, and thereafter a call comes in on incoming call circuit?) in the same manner as for the othercail circuits, the result being that for the call circuits M, and S, call signal controlling relays :4 for the circuit M, 5&4 for the call. circuit X. and 545 for the call circuit S will be operated, this being done in the manner. pre viously described for the relays n for the call circuit M. The signal lamp 47 of the call circuit M has been lighted in the manner previously described to indicate the incoming call on the call circuit M, and in like manner the signal lamp 5&7 indicates the call on the call circuit X, but when the relay in response to the receipt of a call on call. circuit S is made to operate, contacts 

